Loading…

Flash Player 9 (or above) is needed to view presentations.
We have detected that you do not have it on your computer. To install it, go here.

Like this document? Why not share!

MSF Whitepaper on Location Services in LTE Networks

on

  • 5,028 views

 

Statistics

Views

Total Views
5,028
Views on SlideShare
1,610
Embed Views
3,418

Actions

Likes
0
Downloads
92
Comments
0

39 Embeds 3,418

http://3g4g.blogspot.com 1380
http://3g4g.blogspot.in 399
http://3g4g.blogspot.co.uk 386
http://blog.3g4g.co.uk 324
http://3g4g.blogspot.de 113
http://3g4g.blogspot.jp 100
http://3g4g.blogspot.pt 100
http://3g4g.blogspot.tw 95
http://3g4g.blogspot.fr 95
http://3g4g.blogspot.kr 50
http://3g4g.blogspot.com.es 45
http://3g4g.blogspot.it 44
http://3g4g.blogspot.ca 43
http://3g4g.blogspot.se 39
http://3g4g.blogspot.com.br 30
http://3g4g.blogspot.com.au 30
http://3g4g.blogspot.sg 24
http://www.3g4g.blogspot.com 22
http://feeds.feedburner.com 19
http://3g4g.blogspot.hk 15
http://3g4g.blogspot.fi 15
http://www.3g4g.blogspot.in 9
http://translate.googleusercontent.com 6
http://3g4g.blogspot.co.nz 5
http://3g4g.blogspot.gr 4
http://3g4g.blogspot.mx 4
http://www.3g4g.blogspot.co.uk 4
http://3g4g.blogspot.ro 2
http://3g4g.blogspot.hu 2
http://3g4g.blogspot.com.ar 2
http://3g4g.blogspot.co.at 2
http://3g4g.blogspot.co.il 2
http://freesslproxy.com 2
http://3g4g.blogspot.ru 1
http://3g4g.blogspot.nl 1
http://www.hanrss.com 1
http://3g4g.blogspot.ie 1
http://www.linkedin.com 1
https://www.linkedin.com 1
More...

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

MSF Whitepaper on Location Services in LTE Networks MSF Whitepaper on Location Services in LTE Networks Document Transcript

  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALMSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL__________________________________________________________________ Copyright © 2009 MultiService Forum Page 1 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALEditor(s): Shedman Tam, Alcatel-LucentContributor(s): Hunter Lee, ZTEDocument Source: MSF Services Working Group Chair: Bhumip Khasnabish, Verizon Vice-Chair: Frank Suraci, NCS/DHSVersion Number: Msf2009.173.03Day and Date: April 2010Abstract and Executive SummarySupport for Location Services (LCS) in LTE is an important network requirement driven by thefollowing considerations: • Operators must comply with regulatory requirements for emergency services such as E911 in North America, E112 in Europe and 110 in China, in terms of accuracy as well as speed • Location Based Services (LBS) are considered by many to be a key driver for future revenue growth from mobile servicesLocation services for the purpose of regulatory compliance and/or commercial services arealready commonly supported in today’s deployed 2G and 3G wireless networks. The LCSsolution in LTE therefore will be required to: • Provide a cost-effective solution which will meet the accuracy and volume demand of existing as well as new and growing LBS applications and users • Provide a smooth transition with continuous location services from the 2G/3G wireless networks to LTE.This paper discusses the network architecture of such a LCS solution, based on the on-goingspecification work in 3GPP and OMA. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 2 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL Table of Contents1.0 Introduction ................................................................................... 42.0 Problem Statement ........................................................................ 43.0 A Survey of Current Industry Solutions ..................................... 4 3.1 C-plane LCS Solution ................................................................................ 5 3.2 U-plane LCS Solution ................................................................................ 6 3.3 Positioning Methods .................................................................................. 7 3.3.1 Network-assisted GNSS Methods .............................................................................8 3.3.2 Downlink positioning .................................................................................................9 3.3.3 Enhanced Cell ID .......................................................................................................94.0 Use Cases ...................................................................................... 10 4.1 Location Support for Emergency Services ............................................ 10 4.2 Location Support for Commercial Services .......................................... 10 4.3 Proposed Interop Event (based on Maturity) ....................................... 115.0 MSF SWG-Recommended Solution Option(S)......................... 11 5.1 MSF Architecture Based Implementation............................................. 12 5.1.1 Architecture Gap(s) .................................................................................................14 5.2 High-Level Call Flows ............................................................................. 15 5.2.1 Protocol and Control Gap(s) ...................................................................................176.0 Summary and Conclusions ............................................................ 177.0 Acronyms and Abbreviations ........................................................ 189.0 References ....................................................................................... 19 __________________________________________________________________ Copyright © 2009 MultiService Forum Page 3 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL1.0 IntroductionLocation services (LCS) in a wireless network deals with the capabilities to locate target UEs,triggered by either external or internal requests. It makes available the location information toLocation Based Services (LBS) for value-added applications which are accessible to mobilesubscribers or to other third parties.Wireless network and devices are in a unique position to provide LCS due to the inherent geo-location capability of radio signals as well as the user mobility tracking of the system throughprocedures such as paging and location updates.Location-based services for regulatory compliance and for navigation applications are alreadycommonly deployed in 2G and 3G wireless networks. With the availability of smart handsetsand significant increase in wireless bandwidth brought on by technologies such as LTE, it isexpected that the demand for LBS applications will grow rapidly.2.0 Problem StatementDrivers for LCS in the LTE network include: • Complying with local regulation: o Ensure compliance with mandates for personal emergency localization • Developing existing revenue streams: o Enhance existing service utility through greater location accuracy o Provide greater customer satisfaction of existing LBS • Creating new revenue streams: o Offer new services, differentiate on high accuracy localizationThe LTE LCS solution is required to: • Provide a cost-effective solution which will meet the accuracy and volume demand of existing as well as new and growing LBS applications and users • Provide a smooth transition with continuous location services from the 2G/3G wireless networks to LTE.3.0 A Survey of Current Industry SolutionsLCS in the LTE network is a work-in-progress in both the 3GPP and the OMA standard bodies. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 4 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL • LCS C-Plane based solution is being worked in 3GPP Release 9. The functional and network architecture have been finalized, stage 3 definition is expected to be frozen end of 2009. • The U-Plane based solution is being worked in the OMA. SUPL 2.0 with enhancement to support emergency services and LTE access is awaiting validation in upcoming test fests.These two solutions will be described in this section. Many existing 2G and 3G networks havealready deployed either a C-plane or a U-plane solution.While the C-Plane and the U-Plane solutions are distinct in the type of bearers and protocolsused to carry and communicate LCS requests and responses, to control and deliver requiredassistance data and radio measurements, they both utilize and support a similar set of positioningtechnologies which enable the network to accurately locate a mobile user. The set of positioningmethods being specified for LTE in 3GPP will also be described briefly in this section. 3.1 C-Plane LCS SolutionThe LCS Control Plane solution was originally introduced in the GSM network to supportemergency services. The Serving Mobile Location Center (SMLC) is the key functionalcomponent in GSM to support LCS. It manages the overall co-ordination and scheduling ofresources required for the location of a mobile. It also calculates the final location and velocityestimate, as well as estimates the achieved accuracy.The Control Plane solution is later adopted in the UMTS network with the introduction of theStandalone SMLC (SAS) functional component in place of the SMLC in the GSM network.In GSM and UMTS, both the positioning methods and signaling protocols used have dependencyon the air interface technology. While the 3GPP-defined positioning methods for LTE are alsodependent on the air interface, the LTE Positioning Protocol (LPP) is designed to be forwardlooking and to accommodate other positioning technologies in the future.The location service architecture specified for LTE consists of the evolved SMLC connected tothe MME over the new SLs interface. With this architecture, location service continuity ispossible during intra-eNB and inter-eNB handovers without MME relocation.The E-SMLC communicates with the UE for location services and assistance data delivery usingthe new LPP protocol. It communicates with the eNB for eNB almanac and other assistance datausing the LPPa. External or network initiated location service requests are forwarded throughthe GMLC to the MME via the SLg, which performs the LCS user subscription authorizationfunction.The following figure illustrates the LCS Control Plane architecture in LTE. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 5 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL S1-MME UE eNB MME GMLC LRF SLg LTE-Uu SLs M1 Le (e.g. E2) E-SMLC S1-U SGi signaling Serving PDN PSAP IMS data/voice Gateway S5 Gateway connection via intermediate entities modified interface Possible new interface Figure 1: LCS Control Plane architecture with E-SMLC 3.2 U-plane LCS SolutionThe U-plane LCS solution is based on user plane technology which is independent of theunderlying network type. SUPL is the U-plane location technology developed by OMA (OpenMobile Alliance) for positioning over wireless network based on secure user plane IP tunnels. Itis an application layer protocol operating over the interface between the SUPL Location Platform(SLP) and the SUPL Enabled Terminal (SET).The SLP consists of two functional entities: the SUPL Location Centre (SLC) and the SUPLPositioning Centre (SPC). The SLC is responsible for coordination and administrative functionsto provide location services, while the SPC is responsible for the positioning function. These arearchitecturally analogous to the GMLC and the E-SMLC in the C-Plane solution.The core strength of SUPL is the utilization, wherever possible, of existing protocols, IPconnections, and data-bearing channels. SUPL standards are complementary to and compatiblewith C-Plane standards. SUPL supports C-Plane protocols developed for the exchange oflocation data between a mobile device and a wireless network, including RRLP, RRC and TIA-801.SUPL also supports the MLP (Mobile Location Protocol), RLP (Roaming Location Protocol)and ULP (User Plane Location Protocol). MLP is used in the exchange of Location basedService (LBS) data between elements such as an SLP and a GMLC, or between two SLPs; ULPis used in the exchange of LBS data between an SLP and a SET.The following figure illustrates the U-plane architecture in OMA. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 6 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL SIP/IP SIP Push (P-2) MLS Application/ Core SIP Push (P-2) SUPL Agent WAP PPG PAP (P-1) POTAP (P-2) SIP Push (P-1) SMS (Lup) Le/L1 SMSC/MC Lr/LCS-z SMS Telecommunication/ Teleservice (Lup) Emergency Gm IMS Core Lz SUPL Location Platform UDP/IP to Charging SET Home / Requesting / MLS Application/ Visiting / Emergency SUPL Agent SET-to-SLP (Lup) SUPL Location Center SET-to-SLC* (Lup) Lpp Llp Lh/Lg/L2 Home / Requesting / SET-to-SPC* (Lup) Visiting / Emergency SUPL Positioning Center * SET-to-SLC/SPC interface is applicable only to Non-Proxy mode operation Figure 2: LCS User Plane architecture with SLP 3.3 Positioning MethodsThe positioning of UEs is a service provided by the RAN to enable the network to supportlocation services. UE positioning is a technology based on measuring radio signals to determinethe geographic position and/or velocity of the UE. For E-UTRAN access, three positioningmethods have been specified in 3GPP for R9: - Network-assisted GNSS methods; - Downlink positioning; - Enhanced cell ID method. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 7 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALHybrid positioning using multiple methods from the list of positioning methods above is alsosupported. These positioning methods may be supported in UE-based, UE-assisted/E-SMLC-based, or eNB-assisted versions, as summarized in the table below: Method UE-based UE-assisted, E- eNB- SUPL SMLC-based assisted A-GNSS Yes Yes No Yes (UE- based and UE-assisted Downlink Yes [FFS] Yes No Yes (UE- assisted; UE- based FFS) E-CID FFS Yes Yes Yes (UE- assisted; eNB-assisted) Table 1: Summary of Positioning Methods defined in 3GPP R9 3.3.1 Network-assisted GNSS MethodsGlobal Navigation Satellite System (GNSS) refers to satellite navigation systems that provideautonomous geo-spatial positioning with global or regional coverage, for example: GPS, Galileo,SBAS and others. The different GNSSs can be used separately or in combination to determinethe location of a UE.In the E-UTRAN, the GNSS is designed to work with assistance data provided by the network.Assisted GNSS uses signals broadcast by satellites to determine the positions of UEs equippedwith GNSS receivers. Two types of assistance data are provided to improve the positioningspeed and accuracy performance: - Data assisting the measurements: e.g. reference time, visible satellite list, satellite signal Doppler, code phase, Doppler and code phase search windows; - Data assisting position calculation: e.g. reference time, reference position, satellite ephemeris, clock corrections.A-GNSS provides excellent accuracy, and as compared with stand-alone GNSS, it can: - reduce the UE GNSS start-up and acquisition times - increase the UE GNSS sensitivity - allow the UE to consume less power on the handset with the GNSS receiver put in Idle mode when it is not neededThe A-GNSS methods can be operated in UE-assisted mode, where the UE performs GNSSmeasurements and sends them to the E-SMLC to calculate its position; or the UE-based mode,where the UE performs GNSS measurements and calculates its own location. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 8 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL 3.3.2 Downlink positioningIn the downlink positioning method, the UE positioning is estimated based on measurementstaken at the UE of downlink radio signals from multiple eNode Bs, along with knowledge of thegeographical coordinates of the measured eNode Bs and their relative downlink timing. Onesuch positioning method is the Down-Link Observed Time Difference On Arrival (DL-OTDOA),illustrated in figure below: Figure 3: DL-OTDOA methodIn the DL-OTDOA method, the UE estimates the difference in the arrival times of signals fromseparate base stations. Each OTDOA measurement for a pair of downlink transmissionsdescribes a line of constant difference (hyperbola) along which the mobile may be located. TheMobile’s position is determined by the intersection of hyperbolas for at least two pairs of basestations. The base stations have to be time synchronized in order to support the requiredprecision in the measurementsIPDL (Idle Period in Down Link) can be used to overcome the hearability problem arising fromnear-far effect.DL-OTDOA can operate in UE-based mode or UE-assisted mode. In either mode, it mayinvolve the delivery of eNB related assistance data from the eNB and/or the E-SMLC to the UEto aid in measurement collection and/or location calculation. 3.3.3 Enhanced Cell IDIn the Cell ID (CID) positioning method, the position of an UE is estimated with the knowledgeof its serving eNode B and cell. The information about the serving eNode B and cell may beobtained through mobility procedures for mobiles in either active or idle mode, for example, bypaging, and tracking area update. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 9 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALSince the UE can be anywhere in the cell, estimation accuracy depends on the cell size and canbe very poor in cells with large coverage area.Enhanced Cell ID (E CID) positioning refers to techniques which use additional UE and/or E-UTRAN radio resource and other measurements to improve the UE location estimate. UEmeasurements which can improve the accuracy of the location estimate using the Cell ID methodincludes E-UTRA carrier Received Signal Strength Indicator (RSSI), Reference Signal ReceivedPower (RSRP) etc. E-UTRAN measurements which can be used in the Cell ID methods includethe eNB Round Trip Time (RTT) and the Angle of Arrival (AoA).4.0 Use Cases 4.1 Location Support for Emergency ServicesPerhaps one of the oldest and most evident applications of location based service is thedispatching of rescue in emergency situations. Once alerted, typically the emergency responsesystem needs to locate where the emergency, e.g. an accident or a crime, has taken place; andthen to find the closest help available to the victims where again location technology can beuseful. For example, in tracking down the closest ambulance or police patrol that can get to theemergency scene the quickest.Locating speed and positioning accuracy are both critical in an emergency situation. Bysupporting a combined C-Plane and U-Plane LCS solution, the network will be able to assist inlocating the emergency requests from mobile devices which may support only one or the other. 4.2 Location Support for Commercial ServicesWith the increasing popularity of Smartphones, a mobile user’s ability to access internet servicesanytime, anywhere is a given. It is the ability to combine the mobile location technology and theavailable internet services that will open up new ways to enrich consumer services and userexperiences. This in turn will open up new revenue opportunities for mobile operators.There is a broad range of location based applications; some are newly defined, while others areenhancements of existing services. A few examples are: 1. Popular Yellow Page services can be enhanced to “Find the nearest” by combining the traditional service with the location information of the requestor. 2. Navigational assistance is improved with higher positioning accuracy. 3. New social networking services that will provide “friend-finder” presence alerts and facilitate subscribers to connect. 4. “Push” advertisement based on mobile user location to send promotional alerts. 5. Tracking applications such as fleet management and family locator. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 10 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL 4.3 Proposed Interop Event (based on Maturity)Location Services (LCS) for LTE and the C-plane solution are currently being defined in 3GPPas part of Release 9 content. The Stage 3 definitions are expected to be frozen between end of2009 and Q1 2010.Meanwhile SUPL 2.0 specification for the U-plane solution has been almost completed in OMA,and is in maintenance mode for verification, pending test fest activities.Given the above status in standardization efforts, it is expected that an interoperability eventinvolving Location Services may be feasible towards end of 2010/beginning of 2011 wheninfrastructure products and supporting devices are expected to become available.5.0 MSF SWG-Recommended Solution Option(S)Recognising that there is a reliance on a common set of positioning methods, a unified C-planeand U-plane LCS solution can be cost effectively implemented in the network by deploying anintegrated platform to host the positioning function, i.e., the E-SMLC in 3GPP and the SPC inOMA. This combined positioning engine can then feed to either the C-plane and/or the U-planeLCS solution.This LCS solution architecture provides a number of technical as well as cost advantages: • An integrated E-SMLC/SPC allows the sharing of OTDOA and ECID assistance data between Control Plane and User Plane, as well as simplifying the delivery and maintenance of eNB almanac data for positioning use. • An integrated positioning platform lowers the cost of supporting the combined Control Plane and User Plane solution. • An integrated solution offers a smooth transition from multi-technology networks to an eventual uniform LTE network with continuous Emergency and LBS services. For example, UE with SUPL client can use User Plane solution to get Emergency and LBS services, and UE without SUPL client can use Control Plane to get the same service. • An integrated LCS solution can be used flexibly to support future LBS applications available in C-plane, U-pane or both.Optionally, the GMLC and the SLP/SLC can also be optimized by consolidating onto a singleplatform due to their functional synergy.The following figure illustrates the integrated LCS solution architecture. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 11 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL Geolocation Function *Control Plane: E911 S1-MME GMLC UE eNB MME LRF SLg SLP LTE-Uu SLs SLC M1 Le E-SMLC S1-U LBS IMS signaling SGi Serving PDN P- E-CSCF/ Emerg PSAP data/voice Gateway S5 Gateway CSCF E911 AS SGW connection via intermediate entities modified interface Possible new interface *User Plane E911 Figure 4: Integrated LCS Solution with E-SMLC/SPCThe MSF SWG recommends the adoption of the integrated C-Plane and U-Plane LCS solution. 5.1 MSF Architecture Based ImplementationFigure 5 below illustrates the additional functional components and interfaces in the MSFbaseline architecture in order to support LCS in the LTE network. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 12 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL UTRAN S 6d O p e ra to r IP S 4 -S G S N HSS S e rv ic e s S 6a (e .g . IM S ) M1 GERAN S3 Lh SLg GMLC LRF MME S 1 -M M E S10 SLP Le SLs UE/ SLC L T E -U u S4 SET PSAP E -S M L C ENB S11 L ip PCRF Rx SPC S 1 -U Gx S -G W S5 P -G W SGi Figure 5: MSF baseline network architecture with LCS componentsE-SMLCThe key functional component of the LCS architecture for C-Plane solution is the E-SMLC. It isresponsible for the location service function, analogous to an SMLC for GSM or an SAS forWCDMA. It manages the overall coordination and scheduling of resources required for thelocation of a UE that is attached to the E-UTRAN. It also calculates the final location andestimates the achieved accuracy for non UE-based positioning.The E-SMLC communicates directly or indirectly with the serving eNodeB and the UE toprovide positioning assistance data and measurement instructions, as well as to retrievepositioning measurements. The protocols used by E-SMLC for the communication with UE andthe eNodeB are the LPP and LPPa respectively. The E-SMLC also exchanges locationinformation with the core network via the MME.The E-SMLC interacts with the UE in order to exchange location information applicable to UE-assisted and UE-based positioning methods, and interacts with the E-UTRAN in order toexchange location information applicable to network-assisted and network-based positioningmethods.In the proposed architecture, the E-SMLC can either be hosted in the same platform as the SPC;or if not co-located, can communicate with the SPC over a proprietary interface.SLP, SLC and SPCSLP can be a server residing in the network or a network equipment stack. It is responsible fortasks such as authentication to SET and 3rd party LCS client, location request from SET or 3rd __________________________________________________________________ Copyright © 2009 MultiService Forum Page 13 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALparty LCS client, roaming and charging. The SLP consists of two functional components: theSLC and the SPC.The SLC coordinates the operations of SUPL in the network and performs functions of locationmanagement, including: Privacy, Initiation, Security, Roaming, Charging, Service management,triggering positioning calculation.The SPC is responsible for positioning-related functions, including: Security, Assistance DataDelivery, Reference Retrial, and Positioning Calculation.The SLC and SPC may be integrated into a single system, they can also be separated. For theseparated mode, the interface between SLC and SPC is the Internal Location Protocol (ILP)defined by OMA.SET is a mobile device, such as a cell phone or PDA which has capability of SUPL transactions.In SUPL, the interface between SET and SLP is Lup which is defined and standardized by OMA;SUPL is the protocol running over Lup. There are two different communication modes betweenSET and SLP: Proxy Mode and Non-Proxy Mode. For proxy mode, the SPC system will nothave direct communication with the SET. In this environment the SLC system will act as aproxy between the SET and the SPC. For non-proxy mode, the SPC system will have directcommunication with the SET.LRF, GMLCThe Location Retrieval Function (LRF) is a functional entity responsible for the retrieval oflocation information and for providing routing information for a UE which has initiated an IMSemergency session. It handles, where required, interim location information, initial locationinformation and updated location information.The LRF may be collocated with the GMLC or may be separately located. The retrievedinformation is provided to the IMS (E-CSCF) via the Ml interface. While not explicitly shown inFigure x, the emergency CSCF is an additional CSCF role introduced by IMS to control theestablishment of emergency sessions.The GMLC is the LCS server already defined for GSM and UMTS networks. It is the first nodean external LCS client accesses in a PLMN. The GMLC may request routing information fromthe HSS via the Lh interface.After performing registration authorization, it sends positioning requests to the MME andreceives final location estimates from the corresponding entity via the SLg interface. 5.1.1 Architecture Gap(s)The MSF baseline architecture currently does not support LCS in LTE. It is recommended thatthe LCS capability be supported. The additional network components and interfaces identified in __________________________________________________________________ Copyright © 2009 MultiService Forum Page 14 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALFigure 5 for the support of LCS in LTE should be incorporated into the physical implementationfor the MSF baseline architecture. 5.2 High-Level Call Flows 5.2.1 Call Flow for E911 using Control Plane LBS LRF/ UE eNB MME E-SMLC E-CSCF PSAP GMLC 1. Emergency Attach or setup Emergency Bearer 2. Location Report (UE identity, MME IP address) 4. Emergency 3. Location Report Response (E-SMLC IP address) Registration 5. INVITE (emergency call) 6. Location/Routing Request 7. Location Procedure 8. Location Response (Location Estimate, PSAP address, ESQK) 9. INVITE (Location Estimate, ESQK) 10. Remainder of Emergency Call Establishment 11. Location Request (ESRQ) 12. Location Procedure 13. Location Response (Location Estimate, UE Identity) 1. Following an emergency call invocation from the user, the UE will emergency attach to the EPS (i.e., in limited service mode) or if already connected to EPS, request a PDN Connection for emergency bearer services. 2. Once step 1 is complete, the MME sends a location report to a GMLC in the network that is designated to support location of emergency calls. The location report carries the UE identity (e.g. IMSI) and the MME IP address. 3. The GMLC acknowledges the location report. 4. The UE may perform an emergency registration with home IMS. 5. The UE sends an INVITE for the emergency call to the IMS in the network. The INVITE is forwarded to the E-CSCF. 6. The E-CSCF sends a location and/or routing request to an LRF which forwards this to an associated GMLC. 7. The GMLC obtains location information for the UE using a procedure applicable to the architecture. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 15 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL8. The GMLC returns the location information to the LRF which may use this to obtain PSAP routing information. The LRF then returns the location and/or PSAP routing information to the E-CSCF. Correlation information (e.g. an ESQK) can also be included.9. The E-CSCF routes the call to the PSAP indicated by the LRF. Any ESQK can also be sent to the PSAP.10. The remainder of the emergency call establishment occurs.11. The PSAP sends a request to the LRF (e.g. determined using the ESQK) for the location of the UE. The LRF forwards the request to the associated GMLC.12. The GMLC obtains location information for the UE using the same procedure and returns to the LRF.13. The LRF returns the location to the PSAP. 5.2.2 Call Flow for E911 using User Plane LBS1. Following an emergency call invocation from the user, the UE will launch an emergency attach to the IP-CAN over EPS (i.e., in limited service mode) or if already connected over IP-CAN, request a PDN Connection for emergency bearer services.__________________________________________________________________ Copyright © 2009 MultiService Forum Page 16 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINAL 2. The UE sends an INVITE for the emergency call to the IMS in the visited network. The INVITE is forwarded to the E-CSCF. 3. The E-CSCF sends a location and/or routing request to an LRF which forwards this to an associated E-SLP over internal or standardized interface. 4. The E-SLP obtains location information for the UE using SUPL. 5. The E-SLP returns the location information to the LRF over internal or standardized interface, and LRF may use this to obtain PSAP routing information. The LRF then returns the location and/or PSAP routing information to the E-CSCF. Correlation information (e.g. an ESQK) can also be included. 6. The E-CSCF routes the call to the PSAP indicated by the LRF. Any ESQK can also be sent to the PSAP. 7. The remainder of the emergency call establishment occurs. 8. The PSAP sends a request to the LRF (e.g. determined using the ESQK) for the location of the UE. If updated location was requested, the LRF forwards the request to the associated E-SLP over internal or standardized interface. 9. The E-SLP obtains location information for the UE using the same procedure and provides this to the LRF. 10. The LRF returns the location to the PSAP. 5.2.3 Protocol and Control Gap(s)In order to support LCS in LTE, several functional components and their associated interfaces,new to the MSF baseline architecture, are required. They have been highlighted in Section 5.1.The applicable new protocols include: • From 3GPP: LPP/LPPa, ELP, LCS-AP • From OMA: MLP, RLP, ULP, ILP6.0 Summary and ConclusionsLBS application is expected to grow rapidly in the LTE network and has the potential ofbecoming a significant new source of revenues for wireless network operators. Two solutionsare available for LCS implementation: the C-Plane based solution standardized by 3GPP and theU-Plane based solution standardized by OMA. Many existing 2G and 3G wireless networkshave deployed either one or the other solution. __________________________________________________________________ Copyright © 2009 MultiService Forum Page 17 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALIn order to provide service continuity in a cost-effective manner for both C-Plane and U-planeusers, as well as to capitalize on all potential LBS applications developed for either solution, anarchitecture integrating both the C-Plane and the U-Plane solution has been described andrecommended for inclusion into the MSF baseline architecture.7.0 DefinitionMSF baseline architecture: Within the scope of this document, the MSF baseline architecture refers to the MSF R4 architecture [11] + the architectural framework for the 3GPP Packet-Switched Access Tile [12] + the architectural Framework for the 3GPP Evolved Packet System (EPS) Access Tile [13].8.0 Acronyms and Abbreviations3GPP Third Generation Partnership ProjectAoA Angle of ArrivalCSCF Call Service Control FunctionE-CSCF Emergency CSCFELP EPC LCS ProtocolE-SMLC Evolved Serving Mobile Location CenterE-UTRAN Evolved Universal Transmission Radio Access NetworkECID Enhanced Cell IDGMLC Gateway Mobile Location CenterGNSS Global Navigation Satellite SystemGPS Global Positioning SystemILP Internal Location ProtocolLBS Location Based ServiceLCS LoCation ServiceLPP LTE Positioning ProtocolLPPa LTE Positioning Protocol annexMLP Mobile Location ProtocolOMA Open Mobile AllianceOTDOA Observed Time Difference Of ArrivalPSAP Public Safety Answering PointRAN Radio Access NetworkRLP Roaming Location ProtocolRRC Radio Resource ControlRRLP Radio Resource Link ProtocolRSRP Received Signal Received Power __________________________________________________________________ Copyright © 2009 MultiService Forum Page 18 of 19
  • MSF Whitepaper on Location Services in LTE Networks MSF-TR-SERVICES-005-FINALRSSI Received Signal Strength IndicatorRTT Round Trip TimeSAS Standalone SMLCSBAS Space Based Augmentation SystemsSET SUPL Enabled TerminalSMLC Serving Mobile Location CenterSLC SUPL Location CenterSLP SUPL Location PlatformSPC SUPL Positioning CenterSUPL Secure User Plane LocationUE User EquipmentULP User Plane Location Protocol9.0 References[1] 3GPP TS 22.071: “Location Services (LCS); Service description; Stage 1”[2] 3GPP TS 23.271: “Functional stage 2 description of Location Services (LCS)”[3] 3GPP TR 23.891: “Evaluation of LCS Control Plane Solutions for EPS”[4] 3GPP TS 36.305: “Stage 2 functional specification of User Equipment (UE) positioning in E-UTRAN”[5] 3GPP TS 44.031: "Location Services (LCS); Mobile Station (MS) - Serving Mobile Location Centre (SMLC) Radio Resource LCS Protocol (RRLP)[6] 3GPP TS 36.331: "Evolved Universal Terrestrial Radio Access (E-UTRA); "Radio Resource Control (RRC); Protocol specification".[7] 3GPP TS 23.167: “IP Multimedia Subsystem (IMS) emergency sessions”[8] 3GPP TR 23.869: “IP Multimedia Subsystem (IMS) Emergency calls over General Packet Radio Service (GPRS) and Evolved Packet Service (EPS)”[9] OMA-AD-SUPL-V2_0: "Secure User Plane Location Architecture Draft Version 2.0".[10] OMA-TS-ULP-V2_0: "User Plane Location Protocol Draft Version 2.0".[11] MSFR4-ARCH-OVERVIEW-FINAL, MSF Release 4 Architecture Overview[12] msf.2008.160: "Architectural Framework for the 3GPP Packet-Switched Access Tile"[13] MSF-ARCH-013-FINAL: “Architectural Framework for the 3GPP Evolved Packet System (EPS) Access Tile” __________________________________________________________________ Copyright © 2009 MultiService Forum Page 19 of 19